[FOM] The Lucas-Penrose Thesis

[Keith Brian Johnson]

I'm very puzzled about the Lucas-Penrose thesis; perhaps I simply do
not understand it.

1.  It seems as though it says that a machine cannot replicate human
intelligence because any machine has a Godel sentence which it cannot
recognize as true but which a human can recognize as true.

What guarantee do we have that a given human mind will recognize the
Godel sentence of a given machine as true?  Mightn't there be some
machines whose Godel sentences a particular human mind wouldn't
recognize as true?

Isn't it perfectly possible that although I would recognize the truth
of the Godel sentence of the machine replicating *your* mental
processes, I nevertheless would *not* recognize the truth of the Godel
sentence of the machine replicating *my* mental processes?  In which
case, the argument against the possibility of such a machine would
collapse?

2.  Would I have to be able to affirm the consistency of the machine
replicating my mental processes in order to invoke Godel's Theorem at
all?  But if the machine is supposed to replicate my own mental
processes, that affirmation would be tantamount to affirming the
consistency of my own mental processes.  Does Penrose affirm the
consistency of his own mental processes?

Keith Brian Johnson

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